In general, a car audio apparatus combined with a hands-free handset of the cellular phone is available on the market, such as the one disclosed in Taiwan Patent 417920. As shown in FIG. 1, it primarily includes an encoder 60, a host 70 and an activating system 80. The encoder 60 is able to connect with the cellular phone and used to encode the sound signals sent from the cellular phone and the microphone.
The host 70 is mainly composed of a central processing unit and a digital signal processor. The digital signal processor is used to receive the sound signals sent from the cellular phone and the microphone and process these two kinds of sound signals under the control of the central processing unit. The sound signals of the microphone can thus be sent to the encoder 60 via the central processing unit and the sound signals of the cellular phone can also be sent to the audio apparatus via the central processing unit.
The activating system 80 has a silence activating circuit, which can be used to switch the audio apparatus according to the type of the sound signals of the digital signal processor. Thereby, it can automatically switch the audio apparatus to the cellular phone to make the audio apparatus serve as a hands-free handset when the cellular phone is in use.
In this way, a car audio apparatus combined with the hands-free handset circuit that can digitally process the sound signals of the cellular phone and the microphone can be produced.
As described above, the car audio apparatus can be silenced automatically and switched to a voice communication status when an incoming phone call is received by the cellular phone. After hanging up, it will be switched back to audio output status. However, it is not designed for combining the car audio apparatus and the Bluetooth earphone. Besides, it can't support any kind of cellular phone, either.
Moreover, there exists another car audio apparatus that has the functions of the cellular phone. The method is to place a subscriber identity module (SIM) card in the car audio apparatus for the control circuit of the car audio apparatus to access the data of the SIM card and output the sound signals sent from the cellular phone module via a speaker. However, it is not designed for combining the car audio apparatus and the Bluetooth earphone, either.
Consequently, if there is an apparatus that combines the functions of the car audio apparatus and the Bluetooth earphone, it will change the recent competition status of the market and consumers will like it much more than other products. Hence, the inventor of this application is motivated to devote his knowledge and experiences to develop the present invention.